Method for Payload Part Transmission on Contention Channels

1. A method for a user equipment (UE) transmitting a random access channel (RACH) signal to a network, the method comprising: receiving system information comprising information regarding a predetermined multiple number of formats of the RACH signal, wherein the RACH signal comprises a first part of the RACH signal and a second part of the RACH signal, wherein each of the multiple formats define a different combination of a first variable size of the first part of the RACH signal and a second variable size of the second part of the RACH signal, wherein the multiple formats of the RACH signal are predetermined between the UE and the network, and wherein the system information uniquely identifies one format of the multiple formats; generating the RACH signal according to the one format of the multiple formats uniquely identified based on the received system information such that the first part of the RACH signal has a first size corresponding to the first variable size defined by the one format and the second part of the RACH signal has a second size corresponding to the second variable size defined by the one format; and transmitting the RACH signal.

2. The method according to claim 1 , wherein the first part comprises a preamble of the RACH signal and the second part comprises a payload of the RACH signal.

3. The method according to claim 1 , wherein a signature of the RACH signal is selected based on a size of data to be transmitted by the UE.

4. The method according to claim 3 , wherein the size of the data to be transmitted is variable.

5. The method according to claim 3 , wherein the signature of the RACH signal is selected from a predetermined set of signatures based on the size of the data to be transmitted.

6. The method according to claim 1 , wherein each of the multiple formats comprises a unique set of allowed signatures.